The aim of this project is to elucidate the mechanism of glucocorticoid-induced lymphoma regression and to clarify the basis for resistance to steroid therapy in nonresponsive tumors. The following approaches will be used: a) investigation of the possible role of RNA synthesis in the lympholytic process and studies on the influence of glucocorticoid treatment on RNA polymerase activity; b) comparison of specific glucocorticoid receptors in cytoplasmic and nuclear fractions derived from corticoid-sensitive and -resistant lymphocytes; c) examination of the role of free fatty acids, energy metabolism and proteolytic enzymes in the lympholytic process.